High-speed product inspection and cutting apparatus that include an inspection station for detecting defects in a specimen product and a cutting station for removing the defects are in widespread use in the processed food industry. One such type of inspection and cutting apparatus is described in U.S. Pat. No. 4,520,702 of Davis et al., the subject matter of which is herein incorporated by reference.
An apparatus of the Davis et al. type uses a rotating cutting wheel assembly that carries multiple plastic cutter knives angularly spaced around the periphery of a knife support ring or knife guide. A conveyor belt carries previously inspected product material, such as elongated potato strips, carrots, green beans, or other food articles, in a direction generally orthogonal to the axis of rotation of the cutting wheel assembly, which is mounted overhead the conveyor belt. The cutting wheel assembly, in response to commands delivered from an inspection station, selectively deploys certain cutter knives radially outwardly through slots in the knife guide to excise defective regions from the product as it appears directly below the cutting wheel assembly. Having cut the product, the selected knives retract into their respective knife support ring slots until the knives are again deployed.
FIGS. 1A, 1B, and 1C and FIG. 2 are respective isometric, side elevation, top, and sectional views of a prior art cutter knife 10 of a type that can be used in the Davis et al. cutting wheel assembly. Cutter knife 10 includes an elongated shank 12 terminating in a foot 14, thereby giving cutter knife 10 the shape of a leg. A wedge-shaped blade 16 has an inclined, flat top 18 and a bottom 20 from which a cutting edge 22 outwardly extends. A tang 24 that extends from a slide surface 26 of shank 12 is sized to fit in and slide between an inner annular track 28 and an outer annular track 30 of a cam track structure 32, which is shown in FIG. 3.
With reference to FIG. 3, inner annular track 28 and outer annular track 30 receive the tangs 24 of the cutter knives 10 when they are in a retracted noncutting position 34 and an extended cutting position 36, respectively. A knife gate mechanism 38 guides tangs 24 into the track specified by the inspection station (not shown). In FIG. 3, a representative number of the cutter knives 10 are shown in a retracted noncutting position 34, and a representative number of the cutter knives 10 are shown in an extended cutting position 36.
FIG. 4 is a side elevation view of a circular knife guide 50 that has positioned back-to-back and around its periphery two rings of slots 52 each of which holds a cutter knife 10. Each ring of slots 52 of knife guide 50 fits over a different stationary cam track structure 32 and imparts rotational motion to cutter knives 10 so that they slide along cam track structure 32 in either one of its annular tracks 28 and 30. The axis of rotation 54 of knife guide 50 is coincident with the center point 56 of annular tracks 28 and 30. Each one of slots 52 holds and guides a cutter knife 10 as it moves radially between retracted noncutting position 36 and extended cutting position 38. A recessed area 58 along the side walls of shank 12 allows a liquid lubricant to flow between knife 10 and the sides of slots 52 to reduce the stiction forces between them.
One problem with the above-described cutting wheel assembly is that cutter knife 10 occasionally sticks in its slot 52 when remnant product pieces adhere to the cutter knife. There is, therefore, a need for a solution to this problem.